Circulating fan



April 3,- 1934.

c. A. LINDB ERG CIRCULA'I'ING FAN Filed Jan. 22, 1932 2 Sheets-Sheet 1 April 1934? c. A. LINDBERG 1,953,417

CIRCULATING FAN Filed Jan. 22, 1932 2 Sheets-Sheet. 2

#19 Kirb /1629a.

Patented Apr. 3, 1934 UNITED STATES PATENT OFFICE CIRCULATING FAN Application January 22, 1932, Serial No. 588,048 2 Claims. (01. 170-159) This invention relates to circulating fans.

The object of this invention is to provide a fan which is more nearly noiseless than fans of other construction and has increased efficiency.

Other and specific objects will be apparent from the following detail description taken in connection with the accompanying drawings, in which- Fig. 1 is a diagrammatic side elevation showing the fan with, however, but one blade.

Fig. 2 is a front elevation of the fan with its complete complement of blades.

Fig. 3 is a plan view of a blade.

Fig. 4 is an elevation of a blade.

Fig. 5 is an elevation of a blade taken from a different angle from that of Fig. 4.

Fig. 6 is a cross section midway of the blade at right angles to the radius OY. A plurality of blades 1, 2 and 3, are each secured to a bracket 4 which is carried by a collar 5 secured to a shaft 6 of a motor 7. The means of attachment and the motor may be conventional since the novelty of the invention resides in the fan blades and their relative arrangement.

The blades are thin plates of uniform thickness cut to a peculiar and novel configuration and. are bent to conform to a cylindrical surface. They may be said, therefore, to comprise a section of a cylinder, that is, a cylindrical surface. The plan view of the blade 1, shown in Fig. 3, is drawn to scale and taken with the blade stamping in flat position before it is bent. The fan blade may be described as having an entering edge 8, a peripheral edge 9, and a concave following edge 10 which meets the peripheral edge 9 to form a trailingv tip 11.

The arrangement of the blades is such, (see Fig. 2) that when the fan is viewed from the front it presents nearly a solid circular surface. It is important that the entering edge 8 laps the trailing edge 10, as shown in Fig. 2. It is also important that the tip 11 be near the periphery of the fan.

The method of attaching the blade is shown in Fig. 3. The line OR. represents the axis of rotation. The line OY is a meridian of the cylinder of which the blade is a part, and intersects the axes of rotation OR. The plane 0AA may be termed the plane of rotation and is a plane perpendicular to the axis of rotation. The line 0A is here termed the line of attachment although it will be obvious that it does not lie strictly within the blade area. The line OY lies between the line OA and the trailing tip 11 of the blade. The line OY "is oblique to the plane of rotation extending forwardly from the plane of rotation at the periphery of the fan.

The arrangement is such that the fan is almost noiseless in operation, and this has been accomplished without any sacrifice in efliciency over the conventional circulating fan.

Various changes may be made in the details of construction, within the scope of the appended claims, without departing from the spirit of this invention.

I claim:

1. In an electric fan, a blade comprising a sec-' tion of a cylinder and attached in such a manner as to have its line of attachment substantially central of the blade and its meridian, which intersects the axis of rotation, lying between said line of attachment and the trailing edge.

- 2. In an electric fan, a. blade comprising a section of a cylinder and attached in such a manner as to have its meridian, which intersects the axis' of rotation, extending forwardly from a plane perpendicular to the axis of rotation at said point of intersection.

CARYL A. LINDBERG. 

